Leishmaniasis in Sudan 1. Cutaneous leishmaniasis

Cutaneous leishmaniasis (CL) in Sudan is caused by Leishmania major, zymodeme LON-1. The disease is endemic in many parts of the country. The vector is Phlebotomus papatasi and the animal reservoir is probably the Nile rat Arvicanthis niloticus. Clinically, patients usually present with papules, nodules, or noduloulcerative lesions, mainly on the exposed parts of the skin. In 20% of cases the parasite disseminates through the lymphatics, producing sporotrichoid-like lesions. The pathology of the lesion is described. Langerhans cells are the main antigen-presenting cells in CL. They pick up antigen from the dermis and migrate to regional lymph nodes where they present it to T cells. Antigen-specific activated T cells home to the dermis where they stimulate macrophages to eliminate the parasite. Peripheral blood mononuclear cells (PBMC) proliferate in response to Leishmania antigen in vitro and produce cytokines. PBMC of patients with mild and severe disease produce Th-1- and Th-2- like cytokine patterns, respectively. The criteria for the clinical diagnosis of CL are described. The diagnosis is confirmed by the demonstration of parasites in slit smears in 50-70% of cases and in histological sections in 70%. With primers specific for L. major, the polymerase chain reaction is positive in 86% of cases. Since CL is a self-limiting disease, treatment is confined to patients with severe disease.